SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d4e08601d458024cd4959d6792f848757f888dff603660f40fe164dbc014975' 
  AND token = 'UpGYfrLJ5cuCgxJ4+hqPyFbC2KsHdpEvohSxBFhREKI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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