SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4ec9de0af01d435eb3e28a89d64a0584ff1615c3712876caa8f5a31811a10e2' 
  AND token = 'iGbFXd+JWqcj+zdwFVIApZaBKwK/1q/uJTlPZaeGJcM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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