SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fa8d260d312193a47ff6314ac5799a6f15f167696a878098042fad006959cca7' 
  AND token = 'A1U5BhuVQlGrIaZbgiprhk0u8OvTThYraXzFpMGed20=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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