SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db3d0af19b47aa8cfdecb2908484a0d79aca08742a6674a1ad43a7fcff763658' 
  AND token = '+P1LHMaY7oXulBG5Uf2vadT61MxHDj3EgRweOpN/ik4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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