SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'afb3e5c065236ac743d3d51c0f753f579232889cd478d6b578bed75a783739aa' 
  AND token = 'sdeBy7WcJlUlMOd0emtuv9xVKoVO7DGltGeg48WSquw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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