SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a99a1932cefa873685418b59979323433affdc0a06a78e0a3f2bf67a3fd2a5ba' 
  AND token = '0vrswL0FOcMiZLeBhFvoQC6KxsLetYBWxO9VYsVjk8g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}