SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e87dffa674fd9c471358674bb8ff3c7cc49fb75c923210aaf80c24620e01f715' 
  AND token = 'WMX2frFYtwZw+2ZisbSrduS8hT72JYq+5IdUSWnb1Rw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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