SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3facf8fe255c4246472b5d717790f88a8162989e025292b3c34e76d036f7b135' 
  AND token = 'ebxO6WqEoVQCjK16nAOQklspchERVmuaedZZZeYtzZ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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