SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90fe165ade118ef3687c4ceafe6d0b4f643ff7e84b167dfccfc1354fdd5254af' 
  AND token = 'WvEAD4APBZdfO+ZT5apomsepOl/QWmiTKLOkZ+Upq7g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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