SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a31077c5b5a9022546349f3f76f6840d992243c99e6dce26eda7a87fb6ed78af' 
  AND token = 'aDWnfD9nLpcLBrmFjFkbNc52q3Ianj5JobvfjmE8tPs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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