SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39bc9838d31bd460ec7a8160f429ba352c5093734985fda44a083f24a58a5dad' 
  AND token = 'RiGy16IcLjQ2Fi19eXNPccFs3NSsu0YueKhqrsqRMhw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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