SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '74b31fb47a48f170e61f0fcb2485c1cb81714700f308f343fe131eb4a49652e8' 
  AND token = 'B+VXLm6cKPRkhsFmwBA0+hQRYZZr5f8fk+UKYTaH2Jg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00077

JSON explain

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