SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b92cd5bbf667998e5e754db98676d6e7c648f7478c013e370370b6efd47d6cd0' 
  AND token = 'qt5P0chLn/jaK1v/iYtv75+B0BwVTFG31s4VQOwlzcE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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