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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f68f15494e6fa70baca862c81c9e604f856dc19c4ebafba5eb25ccde53e6ecc' 
  AND token = '0nGwyBvDHHtiWTeyZL4tKlCIFRd6N/888WxLjinE50M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}