SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '635588727ff13302b2e63d5b4c86f3c68ee5157fe7f55a4f1f39f72cec5ee9a6' 
  AND token = '49Dqhl8vkkqN4FUDmgBiz/lxzFFCJ4j+1eGOusBAglo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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