SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '652b4c3d7cc9c465d5aed2f300ec588105cbc37ed65bffb19e121ed3cee13f57' 
  AND token = '1MjtxyzbwcJhG1wRR1lGcNWA5htAa41pujPkQpVFulc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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