SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20d8e679393eaced9d0afc6c0f7b6fb2d14f0652fe8644af4bd563bec9e4dad8' 
  AND token = 'vxhh3RWSyFbhGrmdyv5ONAO84crjZTTSq3dDxXfHWlk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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