SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '848a79afc2ac0ee8228bc80db7627807140fded4892edd4fe5cf7c08f9751bf1' 
  AND token = 'yU1W0/PnVPqX/kqBq4hWdT3ke3lLyxM4zLfMqqSbYcg=' 
  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"
    }
  }
}