SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7f429bc38af20c45ef89266994a7c124c131328a3457882e8f59a4c09773e69' 
  AND token = 'USm6/dgMe3zjF/tmlPHtIsIQ+Rj3fbGVF+Wp/s79q3s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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