SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68ec6df3f5afabe510d46ac42893825b78095ac8c49e734a9c15de44e2597a69' 
  AND token = 'qMWUvCyLui4AxINep7ha1Js8LK/uCPk5bw8Wkwm/iyk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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