SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a01e24d6a900bde1fc7559df489c42127748bf4e295a2c67326c53e8579f0588' 
  AND token = 'lfh01DPo3vuM6ytBGTknXRLKvrWi9UXdoQr4wZDgXns=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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