SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '0b298665b6f49f5496bbcb7e73785b4eaf31ab355e3d068a1231921f07779b12' 
  AND token = 'QAU/sowRPa97JGvvqVOpoVPV7xa4Tn92p/yoKkD+7XI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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