SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '333793acad0aa454f1c9b4c8b86c12a26d93b3671ef75d116e25d12d9dbe8836' 
  AND token = 'SEipFHETCPWwCLQRLhnM1K3bFQJZ8jMgaUHQj3Vje+s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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