SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7d1916b13cb4fd03126ee4a04c7a7cbeccd9dc3db4d618ca3f464a6b66347562' 
  AND token = '/XvUPLhBee1LvQeOMa5lt4EYoUohWWjBILIT0JBjniU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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