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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec53842d66d1b29a59d0caa6903b77e3f37b8a0071b6b4b017c1ba1483413237' 
  AND token = 'j4tBwA6Yg1th5R+0yl6ECUTCjy26aKQbmi4Qn2S7e8M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}