SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '19adb8b314ffba830eaf1ab4ad2241729cabadf38a6dd3d0bd8fc2dff90ffba5' 
  AND token = 'FnEQ8ht5hwjPNSmSjVAIzWHbhsOiTRzD0ByjiblMfjM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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