SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d52acac6d3a27cada4613a80ddbc3f2fb8bd0e2ee6afb830e901b6a7cb2f864' 
  AND token = 'cxHR5YSsdno0XgHxvbpsBNUDO+4ARFsQ3orpFuvd2FI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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