SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a991d82a1a6878d753997f45b0e3ad9a95db6c0708280508e990aed99d34be2f' 
  AND token = 'Q3xkY5MkZkz94pyqqWp0a5wJIcS6S4Y4Z0GA4RO4WLo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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