SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '09b738125e51f680bca4d7f408a2e54114a097d85cac1e4b838315a40c3f2486' 
  AND token = 'lBrWOsUvHVSqn17RxvEvFJE3nMVAAoMz65Y69PhC8jM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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