SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '551b9572810106e533ac410cfa256eecc2c452a696c15aaa360797c3f92dfdde' 
  AND token = 'ZFonbPAfKXph1lWolDdXLnH88cL7e8qB03Z7AEmZbig=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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