SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac6d758ee487f24476858c3b952adc5eec21203ffde12c5fb01d38f583658400' 
  AND token = 'uJRfjArqx5J//tQJ3KsfAMLTQxZjis8Zv1hzAr47ncs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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