SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b90ee30b930d8e8e1f0f06c5b4ee24c2980d2fde0d58647e793660927c1a06f4' 
  AND token = '/mRqSKYOgzd+wqi9vCclHO3UDoRep38aQXklF/h8TsE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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