SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99d9c1986479f939fafea0585c28fec4440bffab4c9597dd199481adb1432657' 
  AND token = '39Pow83oG+bnUbSEUOnkK2JIjtR9G3btTuPwmXOgBRY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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