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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a0c6dd3e4b0002e93463a6a8251de04ae62bc9e94efe6f4ed8fa4abbe0837236' 
  AND token = 'e44bQA8yDbQvVctNIakSsItYbcmYItcP4VYr0GUPBZI=' 
  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"
    }
  }
}