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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb5e554170d1e1cb7b784706826c5d4b7b6abd02e9bb8d4a4ef7836a7e71f9d6' 
  AND token = 'LgRjfa1BvzeGu60n1FD146xwJwPw7LvefB8TSf2fM/Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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