SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91df1fc48ad453d41cc433ae1672b85c2ec93d74186307eb391f377aa040bffa' 
  AND token = 'zFK9Tl4RzKxAqzIejIkV4lJpBmfAW6GL79PL/hUsNnk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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