SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e309e921ead9c4a7c458467bcde47a0af917f164648b9e83aa04f119ba199698' 
  AND token = 'PzUQt3yn6d+psVpQXrc516neVo7uhqMX7lOLIRJGW/c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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