SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '67dacc3e60687209fc890c05c30f311181ee360554a5c178e7fe475cfeafa952' 
  AND token = 'znD2alZpDlYRLDcipesmh+KRFmiBC2ygqKBh3Yrpbj4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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