SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81307b5cb572aa48765280103c2e3e00a47265914fb4571fb0186e329cd4614f' 
  AND token = 'hbUB0tt1HdREkrJRzmTOnh/HxYhhHs6CfiOyB8nVTUY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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