SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '743602773898c3d23cfbfd1562412136d235f345f93a4d4b99c9d2c47f936df9' 
  AND token = 'TVxIvS7yrPmShLo8RGC1lsbe2q48/xHaIgh5VLm7wu8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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