SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6d9811b888ea5f7298b21b843f10ac7e49ee61a99a0666331467e4625b22564' 
  AND token = 'ziFd+ZIe0QeE1JiEQU3kQJjdlxO6fSd4sZ+qDjfPUeE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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