SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c14f713b497299a219869bc2da36208bd8ea0e86678912f84f51396d038fdc1' 
  AND token = 'u4lQ04bhSdZ+WQesnBriiTmSiWwf0WE+wlvcHMFSmS0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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