SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c0105663bbfe8fea66c6d709a179d7f40e69555874ca8688680ae334bee826f' 
  AND token = 'mNvOmNj2xo/Zn1gPUaglTzAkS0fc2U7SPa9+Ohw8hCM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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