SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2f6f3558f01ea4ed5bf0a2d10ba6c2a8498e7d9e7d2535596c48e4bad17c2d61' 
  AND token = 'Onr1ggw3aQwSGlKifFXWjenIYvGl+ldsQv6TzPPtPWM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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