SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '618ff3912099b2eff007df7fd1fae37a5eaf50da0ec8d1850e053abadca67f70' 
  AND token = 'MXLRGsqb98WEiWQAfnZbiO8vsdZoqwkWM/3N5oUlJHM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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