SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a743de244270ffe1b231185f1c3249153186fff2d663a3fa8dc42d8365a5198' 
  AND token = 'vAgzH+RFAoNKe4ltzw91cIPtPiCLFIFxJKPL/vIcoVQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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