SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb784ad9989609e80b29283195a33626d74a71d79dca73bf4b5cda57128b115d' 
  AND token = 'P3qIFr7IHzOgCaVaoaUScaAHdOk8T4/gd7LstlXko6g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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