SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f081fc24876e121d72bff29450a4d4dbf0399f8fefda9403b24d8f6ed8115840' 
  AND token = 'B5jtSv+PwTVaFIeljEcUZibc2Ko7JokqAsiyyEWQdG4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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