SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfc69c2abcfbee26711d6975aeed984bcbcb6c779bee638e9fd09a4ec972aa6a' 
  AND token = 'zgKj1vbMv/DcS0nSt1kxDWyFGMQfhlkmwKM3XwwsIok=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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