SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79698af700f783c81256a45f1219536e0e1638b5b72bdd9843b95b53ebc0f066' 
  AND token = 'KUG20h9nYY/Qsq7RWKfBJaLTJfQwVQZ3y9g8zLwn8zg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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