SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd21804c83fe5ff07cc8347a5a56d60f67bf1b32c5ce2749e6ca0c90dc8210858' 
  AND token = 'qSEhYPGGJmLhQPJt/STAlW4jjvRu3hXvgZ2Mxd2+0tk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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