SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0390c1d0cdda8cef29e171398300939a7d64e86d08ad813ce49389e2b5fa8b4' 
  AND token = 'rc47AiQGc1DuJXBsg5zg5/LINaEcuDe6EOSKwZdwxNY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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