SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '555bc7ca084cbee304f53ca1bfbd7c4269522b781b417479a84f53abcdd4b959' 
  AND token = 'FwqBRmhdjFVHgxHDJzBumPkIVJnMW7eSnG7qVuMLXDk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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