SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83735f49fba5f333484751c17e2ba859b0137538a4369e061130f374cd0ba91d' 
  AND token = 'inGLYG9OaZCtQY2mojSS+AErAwEGafeuYZXsJhshLxA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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