SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '126c2bf4f656d93aecb3eccfc59d179103fbc6c94b9bde4ada03eb94ecafc7bd' 
  AND token = 'Ji8YkI/qgrvOECkEZgppWpseIDIg+vGApcYJSC947aw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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