SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c32b4251062bbe0f25e474c7119e168c796b7789e176d831855b41a3396bc30' 
  AND token = 'GASbpae8lGqjaiUAXVXQEEYF5bJYwKQ5htRZqCDITTc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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