SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8b819f1d9a904646f19fdec67faaa0b66c22f83cf82dc8a4a943d92e27d6714' 
  AND token = 'U95kUtUY+tbhv8Yv3MWZpXtQPWGPgSnXKH4oOKN0uZI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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