SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f352684d936b8a66d423c5c86c13a012418aa13a6f62184a54ad9cc817ee7f08' 
  AND token = 'y7URxjtPaV1/uTjaGMB47tU9CEU68Q/BtYuUHuMlRbQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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