SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4eff43503ca806134a278a9a442fcd7dd75bdaec908528251714c037e752f3d0' 
  AND token = 'WVNK36RYuFstFlIMPcqXM1KRb2MUWLEOIhNNM6LOCg8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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