SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a04224c45d5bbef4fc86bc0cb045375f361e9caab3be136782d940dc36c362f9' 
  AND token = '5hByBDF3sTpLr5ktjMHgiTLMBTgJmV3+2klvtiAzSzo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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