SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '955f2c37ccaafdab7cd26ac54c31b7ee4e4e3bc47ec3da896b60a26f6ab347db' 
  AND token = 'MSNQj1Rd3y6u+BoIxHwhZKjeVvEPuqO2wSYK269ANJ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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