SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '439ff4365544820856257b11e44df69f880a3a3e32969f5865ad6ac1ef97b4e8' 
  AND token = 'JOMTanDpJbdvYd/68BxZw+RB22dDoz+XrvA13kVnWn0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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