SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21b48dfbc7a83cc6dc8f438bd506b330b8bf927522834fb7faacaa3d6544af0d' 
  AND token = 'ckhRiKNTXSS2cuoQzoNgny0riIaRlwRgh+FQKkSl198=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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