SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dce6fa9bda9aa0520a24f795628d7db8c1e9dde69b86f52f1884f714ee2d2798' 
  AND token = 'TQwfVNDCHw3X41f/3bKV/hJjki5zw9sIjHlYs5Dp6eQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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