SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3bf850f0ca138b1ee28afd2b176f28fc35656f359fcc12a51f808434df7e276c' 
  AND token = 'hkLeLq702qZSVQ1wMtz+OLLE1vzBcPQ8Y4gfIlWs3Tk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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