SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '273e839d0ab02a60169a918222232598d2cf292023dffb329795a7584ee01930' 
  AND token = 'gpPH5lgvKj+cFnt4XjXc3U6RMpWZsLlv057q8oQJ4s4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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