SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '666f9adf4543b329bbcde6a9856208d00add21d5809e9dd5a70403b8cb71d9ab' 
  AND token = 'rousvwXB2PJsfjQhfle2IBMbmsZ7KsfWgfTsjSYi8MA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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