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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9238dbf59e1e712907810d1d736f918b9d48d71fad39beaf9cc01b1bd57ab5eb' 
  AND token = 'sDjNbzIn4kWgJgd5RLuyNfaY4zDtN0rhrf2q8wr2Fo8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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