SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3d3071ff9005fee9467463a5fad420952f327b2f12abf59244bd281e03f20d3' 
  AND token = 'Xnlv/PDMKZYdj4Xz5H+ar+p2VtFdopW86ROOJVhax2c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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