SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d6b8e14e6fe578fba08544edb7c6cacf1c24a640395ca1cf3a2facc63d3cb7a' 
  AND token = 'mgGRPrUtwH248S9+rWY+XDu0wnhWKg3gm/4VRBSQmBM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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