SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6924381f204365a0a4ce931458a70ea7a1b848120e2beeefbf3b68afe55ce63c' 
  AND token = 'uiOyYBEOOV093yRnbOvGimx/2eB4fYk2o/xFifTN8oM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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