SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9419f71e7959dbd3d125aa93a59821602cb66e273de67e2377919534b13822b0' 
  AND token = '9q43p0SYmjrhHzjdy8biLts1wqmdOgopyifW6n3UsgM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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