SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '147bb2ecde00861199881a5a58d7026763161f0d3c05d83062a85748dce1bce8' 
  AND token = 'xs9s6duYvKz85ePYBy5znKeIKceX+obLbgIRTVjeNYs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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